This application is a national stage of PCT International Application No. PCT/EP2009/001179, filed Feb. 19, 2009, which claims priority under 35 U.S.C. §119 to German Patent Application No. 10 2008 010 828.6, filed Feb. 23, 2008, the entire disclosure of which is herein expressly incorporated by reference.
The present invention relates to a battery having a plurality of individual cells.
According to the state of the art, high voltage batteries, such as lithium ion batteries, are known for vehicle uses, which are in particular constructed of several individual cells interconnected electrically in series or in parallel. Thereby, poles guided from a housing of the individual cells can be electrically connected by means of cell connectors on the one hand, wherein connection contacts for monitoring functions (e.g., cell voltage monitoring) are provided. On the other hand, with bipolar individual cells, in which a plus and a minus pole are placed directly on parts of the housing that are electrically insulated with regard to each other, the parts of the housing forming the electrical contacts are connected directly in a form-fit or force-fit manner. With such as force-fit connection, connection for measuring connections, for example for the cell voltage monitoring, is not possible.
One object of the invention, therefore, is to provide an improved battery, which in particular overcomes the disadvantages given in the state of the art and which can be produced in a simple and cost-efficient manner.
This and other object and advantages are achieved by the battery according to the invention, which comprises a plurality of individual cells, whose poles are electrically interconnected with each other in series or in parallel and form a cell assembly, with each individual cell being surrounded by a cell housing formed of two cell housing side walls and a cell housing frame (2.3). The battery according to the invention is distinguished in that at least one of the poles of a respective individual cell has at least two voltage connection contacts. An arrangement of connections, in particular of different voltage connection contacts as e.g., high or low voltage connection contacts (also called HV or LV contacts) can thus be optimized with regard to installation space and function.
The different voltage connection contacts are thereby conveniently electrically connected (in particular in parallel) within the cell using one of the electrically conductive metallic cell housing side walls, so that no additional connection elements, as conventional cell connectors, are necessary. A simplification of the assembly of the battery and thus a cost savings is achieved thereby.
In a possible embodiment, a first voltage connection contact forms one of the poles of the individual cell and the second voltage connection contact forms a measuring connection. The poles of the individual cell are thereby formed by the electrically conductive, in particular metallic cell housing side walls in a manner that is simple and saves installation space, wherein the pole contact with different polarity of the respective individual cell are placed directly on the cell housing side walls that are electrically insulated with regard to one another.
In a further embodiment, the different voltage connection contacts can be arranged at an arbitrary location independently of each other. In a possible embodiment, the voltage connection contact forming the pole is one of the cell housing walls. The other voltage connection contact formed as a measuring connection is designed as a tab-like extension and projects radially from the corresponding cell housing side wall in an arbitrary direction. By means of these different configurations, voltage connection contacts formed using an individual cell housing side wall can be adapted to the voltage and current, and to their functions, in an optimum manner.
The poles of different individual cells are conveniently interconnected electrically by contacting the cell housing side walls of the individual cells. The individual cells or flat cells are contacted with each other in the axial direction in particular in a cell assembly formed of flat cells. This represents a particularly compact construction which saves installation space.
In a preferred manner, the cell housing side wall of each individual cell provided with two voltage connection contacts has a measuring connection as a voltage connection contact. The measuring connection is conveniently designed as a tab-like extension projecting from the cell housing side wall, which extension is electrically connected to an electronic component, in particular an encapsulated electronic component. The electronic component preferably has devices for a cell voltage monitoring and a cell voltage balancing, so that a same voltage level of the individual cells, and thus a higher reliability of the battery, are always ensured.
In a further arrangement of the invention, the individual cells and/or the pole contacts of different individual cells are connected to each other in a force-fit, form-fit and/or material-fit manner. A durable electrical contact between the poles of the individual cells is thereby ensured in a simple manner.
The individual cells are additionally formed of an electrode stack arranged in a cell housing, wherein at least electrodes with a different polarity are separated in an insulating manner from each other by a separator, preferably a separator film. In a particular manner, an edge region of the respective electrode film guided to the outside of the electrode stack forms a pole contact formed as a current drain tab, whereby an elaborate contacting of electrode film and pole contact is omitted. This type of contacting is at the same time very safe against at least many, in particular outer influences such as impacts or vibrations.
Current drain tabs, that is, the pole contacts, with the same polarity are connected in an electrically conductive manner to a pole. The pole contacts of a pole are further pressed together and/or welded in an electrically conductive manner.
By an arrangement of the electrode stack in an in particular electrically insulating frame which passes around on the edge side, an additional insulating arrangement can be saved in an advantageous manner. The manipulation of the individual cell is further eased or designed in a safer manner.
In a particular manner, especially with bipolar individual cells, the contacting of the pole contacts takes place directly to the cell housing side walls lying opposite to each other, in particular flat sides of the cell housing. These cell housing side walls, in particular flat sides, are electrically insulated with regard to each other by means of the cell housing frame. In this manner, pole contacts (=current drain tabs) with the same polarity are directly connected electrically to a cell housing side wall (=cell outer wall), preferably a flat side of the cell housing, in particular a flat cell, so that the cell housing side walls form the electrical poles of the individual cell. The pressure tightness of the cell housing of the individual cell is also not weakened, as a contact feedthrough of the poles does not take place. An improvement of the tightness of the interior of the cell housing with regard to a passage of humidity is hereby also directly connected.
According to a sensible further continuation of the invention, at least respectively one electrical connection element is arranged at a cell housing side wall of the first individual cell and a cell housing side wall of a last individual cell, so that a simple electrical contacting of the battery is possible.
In one arrangement of the invention, the cell housing frame has two material depressions electrically insulated and spaced from each other, in which are arranged the pole contacts of respectively one polarity formed as current drain tabs. In a sensible manner, the clear height of a material depression in the direction of the stacking of the electrode films is the same as or smaller than the corresponding extension of the associated pole contacts stacked above each other in an uninfluenced manner, and their depth measured parallel to the flat side of an electrode film is larger than or the same as the corresponding extension of the associated pole contacts. The poles are thus held safely in the material depressions and can be pressed with these in an electrically conductive manner with an in particular tight connection between the cell housing frame and the cell housing side walls.
In order to discharge lost heat developing in the battery, a heat-conducting plate is provided for cooling the battery. In an advantageous embodiment of the invention, a heat-conductive material is introduced between the heat-conducting plate and the cell assembly, which is preferably formed of a casting mass, a lacquer and/or a heat-conducting film. This leads to an increase of the heat transfer between the cell assembly and the heat-conducting plate and thereby increases the performance on the one hand and the durability of the battery on the other hand.
In a preferred manner, at least the cell assembly and the heat-conducting plate are arranged in a housing frame, which is especially formed as a clamping element surrounding at least completely the cell assembly and the heat-conducting plate, in particular a clamping strap or a clamping frame.
By one or several of the mentioned measures, it is possible to simplify the construction of a battery and the contacting of the individual cells with an inexpensive manufacture, wherein the poles are at the same time safely protected from foreign matter, in particular humidity and following from that from corrosion by the use of a sealing element.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.